---
title: kAudioUnitSubType_VoiceProcessingIO
framework: audiotoolbox
role: symbol
role_heading: Global Variable
path: audiotoolbox/kaudiounitsubtype_voiceprocessingio
---

# kAudioUnitSubType_VoiceProcessingIO

An audio unit that interfaces to the audio inputs and outputs of iOS devices and provides voice processing features.

## Declaration

```swift
var kAudioUnitSubType_VoiceProcessingIO: UInt32 { get }
```

## Discussion

Discussion Bus 0 provides output to hardware and bus 1 accepts input from hardware. See Audio Unit Voice I/O for the identifiers for this audio unit’s properties.

## See Also

### Constants

- [kAudioUnitSubType_GenericOutput](audiotoolbox/kaudiounitsubtype_genericoutput.md)